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authorJosef Bacik <jbacik@fusionio.com>2013-08-14 14:02:47 -0400
committerChris Mason <chris.mason@fusionio.com>2013-09-01 08:05:05 -0400
commit00361589d2eebd90fca022148c763e40d3e90871 (patch)
tree161dfa7f29d5aa907de0fee6bdc487f9a2bcb342 /fs/btrfs/file.c
parent9ffba8cda917c0158857426f0e74b64d0206aaa9 (diff)
downloadlinux-00361589d2eebd90fca022148c763e40d3e90871.tar.gz
Btrfs: avoid starting a transaction in the write path
I noticed while looking at a deadlock that we are always starting a transaction
in cow_file_range().  This isn't really needed since we only need a transaction
if we are doing an inline extent, or if the allocator needs to allocate a chunk.
So push down all the transaction start stuff to be closer to where we actually
need a transaction in all of these cases.  This will hopefully reduce our write
latency when we are committing often.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Diffstat (limited to 'fs/btrfs/file.c')
-rw-r--r--fs/btrfs/file.c11
1 files changed, 1 insertions, 10 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 8cc941e5b3e1..5e7ea996f105 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1339,7 +1339,6 @@ fail:
 static noinline int check_can_nocow(struct inode *inode, loff_t pos,
 				    size_t *write_bytes)
 {
-	struct btrfs_trans_handle *trans;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_ordered_extent *ordered;
 	u64 lockstart, lockend;
@@ -1361,16 +1360,8 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos,
 		btrfs_put_ordered_extent(ordered);
 	}
 
-	trans = btrfs_join_transaction(root);
-	if (IS_ERR(trans)) {
-		unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
-		return PTR_ERR(trans);
-	}
-
 	num_bytes = lockend - lockstart + 1;
-	ret = can_nocow_extent(trans, inode, lockstart, &num_bytes, NULL, NULL,
-			       NULL);
-	btrfs_end_transaction(trans, root);
+	ret = can_nocow_extent(inode, lockstart, &num_bytes, NULL, NULL, NULL);
 	if (ret <= 0) {
 		ret = 0;
 	} else {